Patent Literature 1 describes an example of an electric braking device provided in a vehicle. Such an electric braking device includes a rotor, a friction member, a motor, a conversion mechanism, and a lock mechanism. The rotor rotates integrally with a wheel. The friction member applies a braking force to the wheel by being pressed against the rotor. The conversion mechanism converts a rotational motion of the motor into a linear motion and transmits the linear motion to the friction member. The lock mechanism maintains a pressing force of the friction member against the rotor.
For example, the lock mechanism includes a ratchet gear, a pawl member, and a solenoid. The ratchet gear is an example of a displacement member which rotates in accordance with rotation of the rotor of the motor. The pawl member is engaged with the ratchet gear. The solenoid moves the pawl member forward and backward. Then, the pawl member is moved by driving the solenoid and pressed against the ratchet gear. When the pawl member is meshed with a tooth of the ratchet gear, rotation of the ratchet gear is regulated in a release direction which is a direction reducing a force pressing the friction member against the rotor. As a result, the braking force applied to a wheel is maintained.
Incidentally, when the pawl member is not meshed with a tooth of the ratchet gear, if a command to stop energization to the motor or to rotate the rotor in a direction for lowering a braking force is input to the motor, the pawl member cannot regulate rotation of the ratchet gear in the release direction in some cases. When the ratchet gear rotates in the release direction, the braking force applied to a wheel is reduced.
Accordingly, in the electric braking device disclosed in Patent Literature 1, after a braking force is applied to a wheel by driving a motor, and a pawl member is pressed against a ratchet gear by driving a solenoid, a value of current flowing to the motor is reduced, and an inspection process is performed to detect a decrease amount of a force pressing a friction member against a rotor at this time. Then, when the decrease amount associated with the inspection process is less than a specified amount, it is determined that the pawl member is meshed with the tooth of the ratchet gear, and rotation of the ratchet gear in the release direction is regulated by the pawl member. On the other hand, when the decrease amount associated with the inspection process is equal to or greater than the specified amount, it is determined that the pawl member is not meshed with the tooth of the ratchet gear, and rotation of the ratchet gear in the release direction is not regulated by the pawl member. In this manner, when it is determined that the rotation of the ratchet gear in the release direction is not regulated by the pawl member, after the motor is driven such that the force pressing the friction member against the rotor increases, the pawl member is pressed against the ratchet gear again by driving the solenoid.